Twin engineering to improve the switchability and rotatability of polarizations and domains in ferroelectric and piezoelectric materials

Abstract

A method for forming deformation crystal twins in piezoelectric materials is disclosed. The method includes obtaining a crystalline piezoelectric material and deforming the crystalline piezoelectric material using a load. The method also includes heating the deformed crystalline piezoelectric material in an oxidative atmosphere to a predetermined temperature for a predetermined time to form a plurality of deformation crystal twins in the crystalline piezoelectric material. The method also includes allowing the crystalline piezoelectric material to cool to room temperature, and removing the load that induces the deformation of the crystalline piezoelectric material. Additionally, the deformation of the crystalline piezoelectric material is achieved by at least one of the following: compressing, stretching, shearing, torsion, and bending of the crystalline piezoelectric material. Further, the shearing creates a shear plane that acts as a twin boundary, which separates a plurality of deformation crystal twins with non-uniform orientation.

What is claimed is: 
     
       1. A method for forming deformation crystal twins in piezoelectric materials, the method comprising:
 obtaining crystalline piezoelectric material; 
 deforming the crystalline piezoelectric material using a load; 
 heating the deformed crystalline piezoelectric material in an oxidative atmosphere to a predetermined temperature for a predetermined time to form a plurality of deformation crystal twins in the crystalline piezoelectric material; 
 allowing the crystalline piezoelectric material to cool to room temperature; 
 removing the load that induces the deformation of the crystalline piezoelectric material, 
 wherein the deforming of the crystalline piezoelectric material is achieved by at least one of the following: compressing, stretching, shearing, torsion, and bending of the crystalline piezoelectric material, and 
 wherein the deforming of the crystalline piezoelectric material creates a shear plane that acts as a twin boundary, which separates the plurality of deformation crystal twins with non-uniform orientation. 
 
     
     
       2. The method of  claim 1 , further comprising:
 disposing the crystalline piezoelectric material onto a substrate, wherein deforming the crystalline piezoelectric material is achieved by deforming the substrate. 
 
     
     
       3. The method of  claim 2 , wherein the crystalline piezoelectric material is based on barium titanate, and the predetermined temperature is 500-600° C. 
     
     
       4. The method of  claim 1 , wherein the plurality of deformation crystal twins are (111) crystal twins. 
     
     
       5. The method of  claim 1 , wherein the predetermined temperature is greater than a Curie temperature of the crystalline piezoelectric material, and less than a melting temperature of the crystalline piezoelectric material. 
     
     
       6. The method of  claim 1 , wherein the oxidative atmosphere has an oxygen partial pressure larger than ¼ of the oxygen partial pressure in air. 
     
     
       7. The method of  claim 1 , wherein a number of the deformation crystal twins is at least 100 per square micron in a given plane. 
     
     
       8. The method of  claim 1 , wherein the crystalline piezoelectric material is a perovskite. 
     
     
       9. The method of  claim 1 , wherein the crystalline piezoelectric material is single crystalline.